Cardiopulmonary resuscitation for cardiac-arrest patients is an emergency procedure with a very low survival rate (5-10%). It is commonly accepted that the quality of the chest compressions is of crucial importance for successful defibrillation and outcome.
Detecting return of spontaneous circulation (ROSC) during cardiopulmonary resuscitation (CPR) is challenging. Typically, ROSC detection involves manual palpation for an arterial pulse, for example at the neck of the patient. Manual palpation requires interrupting the chest compressions and is known to be time-consuming, which can therefore lead to reduced blood flow and a reduced chance of ROSC.
To minimize the duration of this type of pause, clinical guidelines state that a pulse-check pause should take no longer than 10 seconds. In clinical practice, manual pulse checks often take much longer than 10 seconds and are known to be unreliable even if performed by expert clinicians.
Alternatively, a reliable and objective measurement to support ROSC detection is an arterial blood pressure measurement, which can be interpreted to indicate ROSC when the systolic blood pressure is higher than, e.g., 60 mmHg. However, this is an invasive measurement which requires placement of catheters and is consequently not always available. Therefore, a non-invasive method that can support ROSC detection during ongoing chest compressions would be a valuable asset.
The reference US 2012/0035485A1 describes that the presence of a cardiac pulse in a patient may be determined by evaluating physiological signals in the patient. In one embodiment, a medical device evaluates optical characteristics of light transmitted into a patient to ascertain physiological signals, such as pulsatile changes in general blood volume proximate a light detector module. Using these features, the medical device determines whether a cardiac pulse is present in the patient. The medical device may also be configured to report whether the patient is in a VF, VT, asystole, or PEA condition, in addition to being in a pulseless condition, and prompt different therapies, such as chest compressions, rescue breathing, defibrillation, and PEA-specific electrotherapy, depending on the analysis of the physiological signals. Auto-capture of a cardiac pulse using pacing stimuli is further provided.
Reference R.W.C.G.R. et Al: “Detection of a spontaneous pulse in photoplethysmograms during automated cardiopulmonary resuscitation in a porcine model”, RESUSCITATION, vol. 84, 2013, pages 1625-32, XP55125349 discloses an investigation of the potential of photoplethysmography (PPG) signals to detect the presence and rate of a spontaneous cardiac pulse during CPR, by retrospectively analyzing PPG and arterial blood pressure signals simultaneously recorded in pigs undergoing automated CPR.
EP 2 883 493 discloses a system for real-time recognition of restoration of spontaneous circulation which uses time-domain and frequency-domain recognition logic. US 2013/0338724 discloses a system which uses two or more physiological signals to detect a cardiac pulse.
Thus, there have been various attempts to monitor physiological signals to detect the presence of a spontaneous pulse. Monitoring of end-tidal CO2, invasive blood pressure, or central venous oxygen saturation, allows for an objective assessment of pulse, but requires a secured airway or placement of catheters. Trans-thoracic impedance (TTI) measurements, and near-infrared spectroscopy (NIRS) are non-invasive, but TTI is strongly influenced by chest compressions and NIRS responds slowly upon ROSC.
While analysis of photoplethysmography data for pulse detection has been proposed, the data is not easy to interpret.
There remains a need for a reliable way to detect ROSC in a non-invasive way and without interrupting the chest compression sequence being performed on an associated patient. In particular, there is a need for a fast, automated, and accurate method to do a pulse check which gives simple to interpret results, so as to reduce the duration of any pauses and to reduce the amount of false pulse determinations. Recording of the electrocardiogram (ECG) alone does not provide the information as the heart may be electrically active but may not produce cardiac output.